How long can a bettas go with out eating?

Answer 1

dry food in a jar or frozen food in the freezer doesn't go bad. But uneaten food that sinks to the bottom of the tank will rot, make the water cloudy, and grow bacteria and fungus that make the fish sick. Don't feed the betta more that it can eat in 1-2 minutes.

Answer 2

Like most fish they can survive a famine of a week or so but they will loose condition if they are not fed regularly. The biggest killer of Bettas is a lack of water quality (Insufficient filtration and water changes) not a lack of food.

Answer 3

About 5 months.